The present invention relates to a magnetic tack for fastening items to soft-magnetic surfaces. Soft-magnetic materials are known in the field of magnetism to be ones onto which a permanent magnet (called a hard-magnetic material) will stick.
Magnetic snap fasteners are known for use as closures. U.S. Pat. Nos. 5,722,126 and 5,933,926, issued to Applicant, entitled xe2x80x9cMagnetic Snap Fastenersxe2x80x9d, relate to magnetic snap fasteners of different configurations. These fasteners comprise a male and a female section which are magnetically coupled at a single position. These fasteners have projections or rivets on each section which engage to assist in the magnetic attraction between the male and female sections by closing a magnetic circuit. The projection or rivets may have holes extending therethrough.
U.S. Pat. No. 4,453,294, issued to Morita, entitled xe2x80x9cEngageable Article Using Permanent Magnetxe2x80x9d, as reexamined and confirmed under Reexamination Certificate B1 U.S. Pat. Nos. 4,453,294, and 4,021,891, also issued to Morita, entitled xe2x80x9cMagnetic Lock Closure,xe2x80x9d as reexamined and confirmed under Reexamination Certificate B2 U.S. Pat. No. 4,021,891, relate to a magnetic closure wherein a solid projection on a first half of the closure engages a solid projection on a second half of the closure, which also contains a circular magnet. The Morita ""294 and Morita ""891 patents essentially describe the same product. These patents show solid projections or rivets. Further, British Patent Specification No. 1,519,246, published Jul. 26, 1978, discloses a magnetic closure, wherein the projections are partially hollow. None of these prior patented devices are practical for use by themselves to attach items to a soft magnetic surface, such as a wall, since they do not have a convenient means for grasping the fastener to put it on or remove it from the wall. The backs of these devices have attachment means for mounting the fasteners to handbags and the like in male/female pairs. These attachment means are not suited to grasping by a hand.
It also is known to use flat magnets, usually containing an advertising gimmick, to fasten items to soft-magnetic surfaces. These flat magnets generally do not possess enough magnetic force to fasten and support more than a single sheet of paper to a surface.
Conventional thumb tacks can, of course, be used to fasten paper items to non-metallic surfaces. Thumb tacks pierce the documents being tacked and damage them. Their dangerous sharp points are a hazard to children and adult users. Also, conventional thumb tacks are not designed with the ability to support and fasten large packs of paper to a surface and cannot be used to fasten paper items to a metallic surface, such as a refrigerator, or white board.
In view of the aforementioned shortcomings of conventional flat magnets, thumb tacks and magnetic snap fasteners, it is an object of the present invention to provide a magnetic tack for fastening items to soft-magnetic surfaces.
It is another object of the present invention to provide a magnetic tack with the utility and ability to support packs of paper and without damaging the paper.
It is also an object of the invention to provide a child proof and safe tack.
To these and other ends, the present invention contemplates a magnetic tack for fastening an item, such as paper, to a soft-magnetic surface, such as a white board, home refrigerator, wall strip, or other magnetically attractable apparatus or device to which the magnetic tack can stick. The tack includes a plate of soft-magnetic material and a non-magnetic cover which encase a magnet. A knob is secured to the plate to assist in handling the tack. A pin or projection can extend through a hole in the magnet to create a magnetic circuit that will channel magnetic flux in such a manner that the magnet will use its power with improved efficiency. The projection may be hollow or solid. The pin can connect the knob to the magnetic tack. Alternatively, the plate can incorporate sidewalls which conduct magnetic flux to create a magnetic circuit that will channel magnetic flux in such a manner that there will be reduced loss of magnetic power due to flux leakage. As another alternative, the magnetic tack can incorporate both a pin and sidewalls. The knob can be joined to the encased magnet in a variety of ways which may include rivets, screws, glue, solder, welding, or any other form of joining.
The advantages of the invention will become apparent from the detailed description and drawings.